1. Field of the Invention
The invention relates to a satellite receiver for a sum signal of a television signal and an energy dispersal signal, said sum signal being frequency-modulated on a carrier, the satellite receiver comprising a frequency demodulator for obtaining a demodulated sum signal, a television signal processing circuit including a decoding circuit and a compensation circuit which is synchronizable with the television signal to obtain the television signal from the sum signal, an input of the frequency demodulator being coupled to an input of the satellite receiver and an output of the frequency demodulator being coupled to an input of the television signal processing circuit.
The invention also relates to a television signal processing circuit suitable for the satellite receiver.
2. Description of Related Art
A satellite receiver and a television signal processing circuit of these types are disclosed in the European Patent Application No. EP-A 0,235,587. With a view to possible interference on earth, an energy dispersal signal is added to television signals transmitted over DBS (Direct Broadcasting Satellite) satellites, in a transmitter for frequency modulation. If not compensated for, this energy dispersal signal will produce unwanted luminance variations and interferences in the synchronization in a satellite television receiver. Therefore, in the prior art satellite receiver, synchronizing signal peaks in the received and demodulated sum signal of the television signal and the energy dispersal signal are sampled during line retrace periods, whereafter samples obtained thereby are stored in a memory to obtain from these samples, with the aid of an integrator, an analog control voltage which is thereafter subtracted from the received sum signal. Since in MAC television transmission systems the horizontal deflection is not synchronized with the aid of line synchronizing pulses and, in addition, the clamping periods in these MAC television transmission systems are much shorter than in the television transmission systems which have been known already for a longer time, for example PAL, SECAM or NTSC, this prior art method is not suitable for MAC video signals. MAC is an abbreviation of "multiplexed analog components"; in a MAC television transmission system, analog luminance and chrominance signals are transmitted in time-division multiplex.